Subterranean continuous loop heat exchanger, method of manufacture and method to heat, cool or store energy with same

ABSTRACT

A subterranean continuous loop heat exchanger is disclosed having a borehole including an entrance at a first end and an exit at a second end and a conduit for a fluid. A direction of fluid flow relative to the borehole is unidirectional, and a major length of the borehole is non-horizontal. The entrance and the exit are separated by a predetermined distance and a first thermal envelope at the entrance and a second thermal envelope at the exit are substantially independent. The conduit is positioned in at least a portion of the borehole and in operational connection to supply and return lines for connection to a ground sourced heat pump or to a heat exchanger system. Also disclosed are methods of constructing a subterranean continuous loop heat exchanger having at least one continuous borehole and a method of regulating a temperature in a structure with a system that includes the subterranean continuous loop heat exchanger.

FIELD

The present disclosure relates to heat exchangers and methods to transfer and/or store thermal energy. More particularly, the present disclosure relates to apparatus and methods related to subterranean heat exchangers with a continuous loop for use with water based and/or direct exchange systems that connect to ground coupled heat pumps or provide underground thermal storage. Heat exchange efficiency of unidirectional fluid flow through non-horizontal sections of the subterranean heat exchanger is enhanced by, among other things separation of the thermal envelopes of the system.

BACKGROUND

In the discussion of the background that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art.

Subterranean heat exchangers exchange energy with the earth by utilizing the earth's ambient temperature at depth. Current heat exchanger requirements and configuration per nominal ton of heating and or cooling are defined by the proximity of a suitable body of water, underground aquifer, land mass area, temperature at depth, and or geology. The opportunity or option to use this renewable resource is prohibitive in many residential dwellings and commercial facilities due to current technological limitations, land mass area, geological conditions or simply cost. In the application of subterranean heat exchangers, there is a need to decrease the physical area required for installation by increasing the efficiency and to make the systems available to a wider percentage of the new and existing structures.

The worldwide utilization of ground source energy for heating and cooling is increasing. The use of subterranean heat exchanger systems or processes is integral to the function of these systems. There are many configurations and methods of exploiting the resident energy contained in the earth. Examples include (i) utilizing water exchanged from a well, pond, river, lake or ocean; (ii) an array of closed loop piping laid out in a coiled or slinky manner, or other such structured systems immersed into a body of water or buried in the ground; (iii) a series of loops buried in horizontal trenches in the ground; and (iv) vertical and or angled holes bored into the ground that contain a closed loop of pipe that circulates water-based thermal fluids or compressor fluids to the depth of the bore hole and returns to surface in the same bore hole.

Developments in recent years have increased the efficiency of water based and direct exchange heat pumps, which have affected the earth coupled heat exchanger design requirements. Advances in predictive software programs have also increased efficiency by ensuring the ground coupled heat exchanger size and the area required for efficient thermal conversion is properly calculated for the demand load of the structure to be serviced. Examples of this software provide recommendations for the amount of space each borehole must be separated from another and the linear footage of borehole required. Alternatively, the programs can provide requirements for other examples of ground coupled heat exchangers and open systems.

Examples for installing borehole heat exchangers include drilling, vibrating, augering, boring, hammering, or jetting boreholes into the ground a specified distance apart and connect them with a variety of header and collection systems. Each of these installation formats can require a large amount of surface area due to the distance or spacing required to separate individual boreholes to prevent thermal communication between them that can reduce their efficiency. This can lead to issues for future use of the surface area as supply and collection lines will lie just sufficiently below the surface as to reduce the effect of short term seasonal surface temperature changes and influence, i.e., typically between 2 and 8 feet under the surface. Another option is to drill diagonally out from the surface or a point below the level affected by seasonal surface temperature changes and influence at an approximate azimuth of 30° to 85° and start each borehole in close proximity to the surface starting point of other boreholes. This is called pad drilling. It keeps the disrupted ground at surface to a minimum. However, one needs more boreholes due to thermal convection between all the boreholes. Caution also needs to be taken that the boreholes at final depth do not impede upon neighboring property or rights of way as defined by surface area property lines. Most jurisdictions have regulations that govern the borehole placement setback required for drilling next to adjacent properties.

Regardless of the orientation of the boreholes, after the thermal fluid transport line(s) have been inserted into the boreholes and pressure tested to ensure line integrity, the remainder of each borehole is filled with a variety of materials from water to specially formulated grout with the goal to eliminate all vacant space and seal the borehole. The different formulations of grout have a designed affect to increase thermal conductivity between the thermal fluid, conduit, grout, and surrounding ground. Increasing the thermal conductivity of the thermal fluid in the lines with the surrounding ground will enhance the energy transfer as known by those skilled in the art. Polyethylene tubing is typically used as a conduit for thermal fluid transport lines in heat exchangers circulating water based thermal fluids comprised of water and optional antifreeze and rust inhibitors in a closed loop.

Another closed loop system circulates compressor fluids directly to the subterranean heat exchanger through tubing traditionally made of copper. The systems utilizing this format have a higher degree of efficiency per linear foot of heat exchanger over polyethylene tubing circulating water based thermal fluid. These systems are call DX or direct exchange systems. Copper has higher energy conductivity properties than plastics therefore the thermal energy transfer is more efficient. In either case the thermal fluid circulates through the subterranean heat exchanger loop and the naturally warmed or cooled liquid passes to another heat exchanger located at surface, usually in the building to receive the heating and or cooling. This is one of several thermal exchanges of energy that can take place.

Another conventional borehole option uses a coaxial configuration of piping or tubing whereby the fluid entering the borehole would travel to the distal end or bottom on the outside of the piping, tubing or casing in, effectively, a separate chamber, and then return to the starting location of the borehole inside the same line. The flow may be reversed depending upon heating or cooling. Another coaxial configuration has the transport line traveling around in a spiral fashion either inside or outside the primary tubing, piping or casing. There are many examples and configurations detailing the movement of thermal fluid starting at the proximal or start of the borehole to the bottom or distal end and returning to surface to those skilled in the art.

In conventional borehole heat exchangers with a vertical component, the thermal fluid travels to or close to the bottom of the borehole and then back to the surface in the same borehole. The tubing or piping can be separated by a variety of clips or spacers or coaxial chambers designed to keep the lines separated to reduce thermal energy transfer from the fluid entering the borehole and the fluid leaving the borehole. In some examples, one or more of the lines carrying the thermal fluid may be insulated. However, regardless of the efforts to insulate the fluid entering the subterranean heat exchanger from the fluid exiting the subterranean heat exchanger, a thermal transfer of energy is present due to the proximity of the line(s) going to the bottom of the borehole and the line(s) returning the thermal fluid to the surface.

There remains a need in the industry for methods and apparatus to move thermal fluid through a borehole heat exchanger in a variety of configurations that eliminate the distal line from being in close proximity to the proximal line, which will enhance the transfer of energy between the earth and thermal fluid. The result is fewer boreholes required to provide the same amount of energy transfer. This process will also reduce installation costs and will reduce the amount of land necessary for a borehole “field,” making the option of utilizing ground coupled systems available to more home owners, facilities and institutions.

SUMMARY

Apparatus and methods related to subterranean heat exchangers with a continuous loop for use with water based and/or direct exchange systems that connect to ground source heat pumps and or a heat exchanger system or to provide underground thermal storage. The methods and apparatuses enhance thermal conversion efficiency in subterranean borehole applications.

A singular or plurality of subterranean heat exchangers are drilled, vibrated, bored, augured, hammered or jetted in the earth and provide for the continuous, unidirectional circulation of thermal fluids from the point of entry in the earth and travel to the point of exit and provide a source of energy for use with ground coupled heating, cooling and thermal storage processes. Methods and apparatus for the circulation and the transfer of thermal fluids in subterranean heat exchangers increase the thermal conversion efficiency. Each subterranean heat exchanger conduit may include features to create or enhance the flow of thermal fluid therethrough by, for example, aiding in enhancing thermal convection of the thermal fluid with the surrounding formation.

The subterranean heat exchangers utilizing the described method and apparatus are more efficient at extracting, injecting or storing the resident thermal energy in the earth, thus reducing the amount of physical land required both above and below the surface thereby reducing costs. This is achieved by positioning the subterranean borehole heat exchanger on a near vertical azimuth for a predetermined distance before changing the angle of the borehole to connect the desired entry point and exit point at the surface. This continuous loop arrangement provides the ability to circulate thermal exchange fluid through the borehole in a single direction, i.e., unidirectionally, and increases the thermal efficiency per linear foot thereof.

An exemplary embodiment of a subterranean continuous loop heat exchanger comprises a borehole including an entrance at a first end and an exit at a second end, a conduit for a fluid, the conduit positioned in at least a portion of the borehole and in operational connection to a supply line and to a return line for connection to a ground sourced heat pump or a heat exchanger system, wherein the entrance and the exit are separated by a predetermined distance and a first thermal envelope of the borehole at the entrance and a second thermal envelope of the borehole at the exit are substantially independent, wherein a direction of fluid flow relative to the borehole is unidirectional, and wherein a major length of the borehole is non-horizontal.

An exemplary method of constructing a subterranean continuous loop heat exchanger, the subterranean continuous loop heat exchanger including at least one continuous borehole, comprises forming a borehole by boring into a strata, positioning a conduit for a fluid in at least a portion of the borehole, and operationally connecting the borehole to a supply line and to a return line for connection to a ground sourced heat pump, wherein a first opening of the borehole and a second opening of the borehole are separated by a predetermined distance and a first thermal envelope of the borehole at the first opening and a second thermal envelope of the borehole at the second opening are substantially independent, wherein a direction of fluid flow relative to the borehole is unidirectional, and wherein a major length of the borehole is non-horizontal.

An exemplary method of regulating a temperature in a structure comprises flowing a fluid through a conduit in a borehole of a subterranean continuous loop heat exchanger from an entrance to an exit, flowing the fluid from the exit through a ground sourced heat pump, returning the fluid from the ground sourced heat pump or heat exchanger system to the entrance, and operating the ground sourced heat pump to regulate the temperature in the structure.

An exemplary method to store thermal energy in a subterranean continuous loop heat exchanger comprises flowing a fluid through a conduit in a borehole of a subterranean continuous loop heat exchanger from an entrance to an exit, flowing the fluid from the exit through a ground sourced heat pump or heat exchanger system, returning the fluid from the ground sourced heat pump to the entrance, and operating the ground sourced heat pump or hear exchanger system to exchange thermal energy with a strata surrounding the subterranean continuous loop heat exchanger.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWING

The following detailed description can be read in connection with the accompanying drawings in which like numerals designate like elements and in which:

FIG. 1 illustrates an exemplary embodiment of a subterranean continuous loop heat exchanger with a borehole drilled in a continuous loop through the earth.

FIG. 2 an alternative configuration of an exemplary embodiment of borehole.

FIG. 3 illustrates an exemplary embodiment of a subterranean continuous heat exchanger with both a non-vertical and non-horizontal borehole orientation.

FIG. 4 illustrates an exemplary embodiment of a borehole positioned under a structure.

FIG. 5 is a cross-section of an exemplary embodiment of a borehole illustrating an example of a fluid transport line and an example of a coaxial insert.

FIG. 6 is a cross-section of an exemplary embodiment of a borehole illustrating an example of a fluid transport line and an example of a twisted ribbon insert.

FIG. 7 is a cross-section of an exemplary embodiment of a borehole illustrating an example of a fluid transport line and an example of a wire insert.

FIG. 8A is a cross-section of a borehole illustrating a raised profile within the fluid flow in the conduit.

FIG. 8B is a sectioned view of a fluid transport line with an example of a raised profile.

FIG. 9 is a cross-section of an exemplary embodiment of a coaxial insert.

FIG. 10 is a cross-section of an exemplary embodiment of a twisted ribbon insert.

FIG. 11 is a cutaway top view of an exemplary embodiment of a borehole with a spiral blade insert.

FIG. 12 is a cutaway top view of an exemplary embodiment of a borehole with a wire insert.

FIG. 13 is a cutaway top view of an exemplary embodiment of a borehole with a spiral finned insert.

FIG. 14 is a cutaway top view of an exemplary embodiment of a borehole with profile tubing.

FIG. 15 is a cutaway view of an exemplary embodiment of a borehole with two conduits, each with a coaxial insert.

FIG. 16 is a cutaway view of an exemplary embodiment of a borehole with three conduits, each with a twisted ribbon insert.

FIG. 17 is a cutaway view of an exemplary embodiment of a borehole with two conduits connected to a header and the supply line from a ground source heat pump.

FIGS. 18A and 18B illustrate an exemplary embodiment of a subterranean continuous loop heat exchanger showing a plurality of chambers or void spaces along a length of the conduit.

FIGS. 19A-C illustrate an exemplary embodiment of a subterranean continuous loop heat exchanger showing a plurality of chambers or void spaces along a length of the borehole.

FIG. 20 schematically illustrates the construction of a subterranean continuous loop heat exchanger including at least one continuous borehole at an intermediate stage of construction.

FIG. 21 illustrates another example of forming a borehole showing the first portion of the borehole and the second portion of the borehole prior to being joined.

FIG. 22 illustrates an exemplary embodiment of a subterranean continuous loop heat exchanger showing a plurality of devices to aid in the placement of a conduit within the borehole.

FIGS. 23A and 23B schematically illustrates another example of the construction of a subterranean continuous loop heat exchanger including one continuous borehole and an example of a system to place thermal grout in the borehole.

FIG. 24 schematically illustrates another example of the construction of a subterranean continuous loop heat exchanger including equipment and a process to place thermal grout in the borehole.

FIG. 25 illustrates a volume of earth 300 in which has been positioned a subterranean continuous loop heat exchanger that identifies beneficial thermal zones and the continuous loop heat exchanger targeting on specific zones.

FIG. 26 schematically illustrates another example of the construction of a subterranean continuous loop heat exchanger including one continuous borehole and an example of using coil or coiled tubing drilling as the method of drilling

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary embodiment of a subterranean continuous loop heat exchanger with a borehole drilled in a continuous loop through the earth. The subterranean continuous loop heat exchanger 10 comprises a borehole 12 including an entrance 14 at a first end 16 where the borehole 12 opens at a first location, e.g. within the strata 18 for a buried system or on a surface of the strata 18, i.e., the ground, for surface systems, and an exit 20 at a second end 22 where the borehole 12 opens at a second location of the strata 18, e.g. within the strata 18 for a buried system or on a surface of the strata 18, i.e., the ground, for surface systems. The majority of the borehole 12 lies sufficiently below the ground level susceptible to seasonal temperature influence 24, i.e., typically between two and eight feet under the surface 26. A conduit for a fluid 28 (shown in cut-away view) is positioned in at least a portion of the borehole 12. In an exemplary embodiment, the conduit can be a tube or pipe formed from a synthetic, a metal or metal alloys, which may have a coating comprised of similar, different or combination of materials on all or a portion of the inside or outside surfaces.

FIG. 1 shows a buried system with the first end 16 of the borehole 12 within the strata 18 and proceeding to a depth (D) from the surface 26 before turning, for example in a symmetric manner or in the same arc, and returning toward the surface 26 at the second end 22 to terminate with the strata 18. The working depth (D_(w)) of the subterranean heat exchanger is measured as the depth to which the borehole extends below the ground level susceptible to seasonal temperature influence 24.

In the illustrated exemplary embodiment, the first end 16 is the entrance and the second end 22 is the exit, although the entrance and the exit can be switched as necessary to facilitate operational connection of the conduit for the fluid 28 to a supply line 34 and to a return line 36 to a ground sourced heat pump or heat exchanger system 38. In one example the ground sourced heat pump 38 is itself operational connected to a structure 40 to regulate the temperature or other environmental parameter thereof. In FIG. 1, the ground sourced heat pump 38 is located within a basement of structure 40.

The entrance 14 and the exit 20 are separated by a predetermined distance (D_(s)). The predetermined distance is selected such that a thermal envelope 42 of the borehole 12 at the entrance 14 and a thermal envelope 44 of the borehole 12 at the exit 20 are substantially independent. The thermal envelopes are shown in dashed lines in FIG. 1. In FIG. 1, the predetermined distance (D_(s)) is large and there is clearly no overlap of the thermal envelopes at the respective ends.

FIG. 2 illustrates a magnified view of a second embodiment of a subterranean continuous heat exchanger 10 where the entrance 14 and the exit 20 are separated by a much smaller predetermined distance (D_(s)). In the FIG. 2 embodiment, the respective thermal envelopes 42, 44 of the entrance 14 and the exit 20 do not overlap, as evidenced by the separation distance (D_(E)) between the respective thermal envelopes 42, 44. An example of a suitable predetermined distance (D_(s)) is at least about twenty five feet, alternatively at least about 10 feet, alternatively at least about 3 feet, alternatively between about 3 feet and about 10, alternatively between about 3 feet and 5 feet. In the illustrated example in FIG. 2, it is seen that at the predetermined distance (D_(s)), a separation distance (D_(E)) of the thermal envelops 42,44 is greater than zero, preferably at least greater than about 1 feet, alternatively at least greater than about 3 feet.

The reason boreholes have a defined linear distance separating them is to compensate for thermal convection and conductivity between boreholes and ensure there is an area sufficient for the natural regeneration of the ground temperature surrounding the borehole. As the energy is being removed or injected into the borehole, the surrounding strata will heat up or cool off over time. For example; the surrounding strata replaces, by warming up the area within the thermal envelope, energy that is removed from the ground when a fluid colder than the median temperature of the earth is circulated through the borehole. This would happen when a ground source heat pump was operating in heating mode. If the boreholes are too close together or too short in depth, then energy transfer between the boreholes and the earth, or vise versa, will be at a rate higher than the earth can accommodate and would result in the ground temperature equalizing close to the temperature of the thermal fluid. In the case of boreholes spaced too close together, the thermal communication would be between the boreholes instead of between the source and sink. This will result in the reduced thermal efficiency of the boreholes in the field, which ultimately results in equipment stress, inefficiency or catastrophic failure. To compensate for closely spaced boreholes, one option is to drill more boreholes or increase the linear depth which increases costs.

The predetermined distance (D_(s)) can vary by application and is selected to be suitable for the characteristics of the strata in which the borehole is positioned, for the dimensions of the site, and/or based on a load requirement of the structure 40, a temperature of which is to be regulated by the ground source heat pump or heat exchanger system serviced by the subterranean continuous loop heat exchanger. For example, where distance limitations are not appreciable, a configuration of the borehole 12 such as is shown in the exemplary embodiment in FIG. 1 can be selected where the predetermined distance (D_(s)) is quite large, e.g., on the order of tens or hundreds of feet, alternatively, at least about fifteen feet. However, in another example, where distance limitations are to be accommodated, a configuration of the borehole 12 such as is shown in the exemplary embodiment in FIG. 2 can be selected where the predetermined distance (D_(s)) is quite small, e.g., on the order of single feet and no more than 10 feet. In the second example shown in FIG. 2, the borehole is essentially vertical at the entrance and exit, which is achieved by forming the borehole with a directional boring apparatus as, for example, described further herein.

In a further example, it is not required that the borehole be substantially vertical at the entrance and the exit for the borehole to have both a small, e.g., less than ten feet, alternatively less than five feet, predetermined distance (D_(s)) and for the respective thermal envelops to have a small e.g., less than ten feet, alternatively less than five feet, further alternatively less than two feet, separation distance (D_(E)). For example and as shown in FIG. 3 in perspective cut-away view, an exemplary embodiment of a subterranean continuous heat exchanger 10 can have a non-vertical and non-horizontal borehole 12 orientation with an entrance 14 and the exit 20 with a predetermined distance (D_(s)) that is small, e.g., less than ten feet, alternatively less than five feet, and with a separation distance (D_(E)) of the respective thermal envelops 42,44 also small e.g., less than ten feet, alternatively less than five feet, further alternatively less than two feet. In the illustrated embodiment, the small value for the distances D_(s), D_(E) are achieved at least in part by the skewed orientation of the borehole 12 and its loop configuration, which resembles a teardrop, although other orientations and loop configurations can be utilized.

FIG. 4 illustrates an exemplary embodiment of a borehole 12 positioned under a structure 40. In this exemplary embodiment, the entrance 14 and the exit 20 are positioned on different sides of the structure 40, such as on opposite sides or on adjacent sides. In contrast, the exemplary embodiment of the bore hole 12 in the subterranean continuous loop heat exchanger 10 in FIG. 1 is positioned to the same side of the structure 40. The remaining features shown in FIG. 4 are similar to those shown and described in regard to the exemplary embodiment of the bore hole 12 in the subterranean continuous loop heat exchanger 10 in FIG. 1.

The direction of fluid flow in exemplary embodiments of the subterranean continuous loop heat exchanger 10 is unidirectional relative to the borehole 12. That is, the fluid flow (F) through the conduit 28 is in only one direction, entering from first end 16 of the borehole 12 and traveling toward the second end 22. Furthermore, the fluid flow (F) is in a continuous loop, in that, after traveling in one direction relative to the borehole 12 from the first end 16 toward the second end 22, the fluid then is ported back to the first end 16 (through the ground source heat pump 38 for example) where it again enters from the first end 16.

In exemplary embodiments, the subterranean continuous loop heat exchanger 10 has a borehole 12 with a major length that is non-horizontal, alternatively greater than 75% of the length is non-horizontal, further alternatively greater than 85% of the length is non-horizontal. As an example, reference is made to FIGS. 1 and 3. In FIGS. 1 and 3, the borehole 12 has an orientation that incorporates a major length that is non-horizontal. Indeed, in these examples, outside of the orientation at the deepest point 50, the borehole 12 is non-horizontal the entire length from the first end 16 to the second end 22.

In exemplary embodiments, the subterranean continuous loop heat exchanger 10 has a borehole 12 where the entrance 14 of the borehole 12 and the exit 20 of the borehole 12 both have a centerline 52 that is within ±15 degrees of vertical, alternatively within ±5 degrees of vertical. In further alternative embodiments, the orientation of the centerline 52 of the borehole 12 continues at within ±15 degrees of vertical, alternatively within ±5 degrees of vertical, until the borehole 12 is deeper than the frost line 24. An example of such an arrangement is shown in FIGS. 1 and 2. Further and in regard to FIG. 2, the centerline 52 of the borehole 12 is within ±5 degrees of vertical to a depth that is at least 50% of the deepest point 50.

To promote thermal exchange between the strata 18, a heat exchange medium 60 can be positioned within an annulus 62 (preferably the entire annulus) between an inner wall 64 of the borehole 12 and an outer surface 66 of the conduit 28. The heat exchange medium 60 is positioned within the annulus 62 at least to below the ground level susceptible to seasonal temperature interference 24, preferably within the entire annulus 62, and contributes to a thermal exchange with a surrounding strata 18.

An example of a heat exchange medium 60 is a bentonite-based thermal grout, such as “Thermal Grout Select” and “Thermal Grout Lite” available from GeoPro, Inc. of Elkton, S. Dak. Another example of a heat exchange medium 60 is disclosed in U.S. Pat. No. 6,251,179, the entire contents of which are incorporated herein by reference. The later is of note due to the excellent thermal conductivity and shrinkage reducing properties. Traditional borehole grout mixtures used cement and bentonite that, while forming a good initial seal, over time the bonding can deteriorate causing air gaps to form which greatly reduce the efficiency of the exchanger. In alternative exemplary embodiments, the heat exchange medium 60 can include a synthetic material to enhance moisture retention. Examples of moisture retention enhancing material are gel additives, such as those found in oil and gas drilling fluids and industrial applications. One aspect of the heat exchange medium 60 is a polymer, which in contact with water forms a gel material. Examples of such a polymer include, but are not limited to, thermal conductive solids such as sand comprised of silica or crushed rock, beaded or powdered glass and or metal or metal alloys. Water-soluble polyacrylamide polymers, biopolymers, guar or xathan gum that in certain combinations that are rehydrateable, and do not crack when dehydrated.

Exemplary embodiments of the subterranean continuous loop heat exchanger 10 circulate and transfer fluids in a manner that the flow of fluid will generate the most efficient thermal conversion between fluid and the surrounding strata. Fluid flow through a conduit at a volume and rate sufficient to correspond with a Reynolds number of approximately 2,500 is generally the targeted flow rate for efficient thermal conversion using subterranean heat exchangers, as known to those skilled in the art. Studies and tests have shown that transitional flow rates such as those used in the conventional ground source heat exchangers with a corresponding Reynolds number of between 2,300 and 4,000 can experience enhanced thermal conversion with the use of flow enhancement features contained in the conduit or by addition of supplemental flow enhancement features.

To ensure the optimum use of flow rate and flow enhancement features, analysis is performed upon the ground to the depth of the subterranean boreholes. The flow enhancement features if employed are to maximize the thermal capabilities of the strata hosting the borehole(s) and are selected based upon the conditions present. Care is taken not to exceed the thermal conversion limits of the strata but to maximize the potential between source and sink as known to those skilled in the art.

Exemplary embodiments of the subterranean continuous loop heat exchanger 10 circulate and transfer fluids in a manner that increases the thermal conversion efficiency between the strata and the fluid. For example, the subterranean heat exchanger can include features to create, enhance or increase the turbulence of the fluid flow therethrough. FIGS. 5 to 7 schematically illustrate such flow enhancing features placed in a fluid flow stream within the conduit, which can include, by way of example, one or more ribs on an inner surface of the conduit, an insert positioned within the conduit and a raised profile on one or more surfaces of the conduit. These flow enhancement features can be used singularly or in combination to enhance the thermal conversion efficiency of the subterranean continuous loop heat exchanger 10.

FIGS. 5-7 are cross-sections of exemplary embodiments of a borehole illustrating examples of a fluid transport line and examples of an insert. In the illustrated examples, a conduit 28 is positioned within a borehole 12 with a heat exchange medium 60 therebetween. Within the conduit, an insert 80 is positioned. The insert 80 can take any of various forms that produce turbulence as the fluid traveling within the conduit 28 moves past the insert 80. In FIG. 5, the insert 80 is shown in the form of a coaxial insert. The coaxial insert has a spiral shape, a spring shape. Similarly, a helical shape can be used as the coaxial insert. In another example, a spiral blade can be used as the coaxial insert. In FIG. 6, the insert 80 is shown in the form of a twisted ribbon. In FIG. 7, the insert 80 is shown in the form of a wire. In each example, the insert 80 includes a series of structures and a series of openings, the combination of which produces turbulence as the fluid traveling within the conduit 28 moves past the insert 80. The material from which the insert 80 is made can be any suitable material that can produce turbulence as the fluid traveling within the conduit 28 moves past the insert 80 and that is not subject to unacceptable levels of corrosion or other failure modes.

FIG. 8A is a cross-section of an exemplary embodiment of a borehole illustrating a raised profile within the fluid flow in the conduit. In the illustrated examples, a conduit 28 is positioned within a borehole 12 with a heat exchange medium 60 therebetween. The surface of the inner wall of the conduit 28 includes a raised profile 82, such as one or more projections or ribs, that are located within the fluid flow in the conduit 28. These raised profiles 82 can take any of various forms that produce turbulence as the fluid traveling within the conduit 28 moves past. For example, the raised profiles can be on a single cross-sectional plane or can cross several cross-sectional planes, e.g., thread-like. Concomitantly and where the raised profiles 82 are integrally formed in the conduit 28, e.g., by molding, the surface of the outer wall of the conduit 28 has corresponding depressed profiles 84. As an additional benefit, raised profiles 82, alone or in combination with depressed profiles 84 (when present), increase the surface area of the conduit 28 in contact with the fluid and the heat exchange medium 60, thereby increasing the heat transfer between the strata and the fluid. Similarly, raised profiles on both the surface of the inner wall of the conduit 28 and the surface of the outer wall of the conduit 28 can be included, which will similarly increase the surface area of the conduit 28 in contact with the fluid and the heat exchange medium 60, thereby increase the heat transfer between the strata and the fluid.

FIG. 8B is a sectioned view of a fluid transport line with an example of a raised profile 82. In this view, the interior surfaces have a raised profile 82. For example the inner surfaces can include a raised profile 82 that has a thread-like or rifled characteristics.

FIGS. 9 and 10 illustrate two examples of coaxial inserts. In FIG. 9, an exemplary embodiment of a coaxial insert having a spiral shape is shown. The body 90 of the coaxial insert spirals in the axial direction along its length. In FIG. 10, an exemplary embodiment of a coaxial insert having in the form of a twisted ribbon is shown. In side elevation view, the surface 92 of the twisted ribbon is visible as it passes through the inflection point 94 formed by the twisting of the ribbon.

FIGS. 11 to 14 illustrate cutaway top views of various exemplary embodiments of boreholes showing different inserts and raised profiles within the conduit. In FIG. 11, a spiral blade insert 86 is shown; in FIG. 12, a wire insert 87 is shown; in FIG. 13, a spiral finned insert 88 is shown; and in FIG. 14, a raised profile 82 is shown.

Various arrangements and combinations of boreholes and conduits can be utilized to improve thermal efficiency and to meet the load requirement of a structure. For example, a plurality of conduits for a fluid can be positioned within the subterranean continuous loop heat exchanger. Each conduit can be positioned in at least a portion of the subterranean borehole and can be in operational connection to the supply line and to the return line for connection to the ground sourced heat pump. The operational connection can be, for example, a header system.

Examples of some of the above described arrangements and combinations are shown in FIGS. 15 to 17. FIG. 15 is a cutaway view of an exemplary embodiment of a borehole 12 with two conduits 28,28′ each with an insert 80. In the FIG. 15 embodiment, the insert 80 is a coaxial insert. FIG. 16 is a cutaway view of an exemplary embodiment of a borehole 12 with three conduits 28,28′,28″ each with an insert 80. In the FIG. 16 embodiment, the insert 80 is a twisted ribbon insert. FIG. 17 is a cutaway view of an exemplary embodiment of a borehole 12 with two conduits 28,28′ connected to a header 100 and the supply line 34 from a ground source heat pump 38. Alternatively to the above described plurality of conduits, a borehole 12 can contain one conduit 28 into which are inserted a plurality of fluid transport lines, each of which can contain a turbulence feature as described herein, e.g., an insert or a raised profile.

In an alternative embodiment, the subterranean continuous loop heat exchanger has a conduit that includes one or more chambers or void spaces along a length thereof. Fluid traveling in the subterranean continuous loop heat exchanger flows into these chambers or void spaces during normal operation. The fluid then is resident in these locations for a longer time than if the fluid flowed only through a constant diameter conduit. This longer resident time allows for increased thermal exchange between the fluid and the surrounding strata, thereby increasing the thermal efficiency.

FIG. 18A illustrates an example of a subterranean continuous loop heat exchanger 10 showing a plurality of chambers or void spaces 102 along a length of the conduit 28. As seen in the magnified view in FIG. 18B, the chambers or void spaces 102 are incorporated into the conduit 28 itself, for example, during the manufacturing process of the conduit 28, or can be, in another example, regions of the conduit 28 that expand under a pressure applied inside the conduit 28.

FIG. 19A illustrates an example of a subterranean continuous loop heat exchanger 10 showing a plurality of conduits along a length of the borehole 12. As shown in one instance in FIG. 19B in cut-away view, the borehole 12 has three conduits 28 through which the fluid flows. The conduits are surrounded by grout 60 ensuring a positive thermal connection with the surrounding strata. The conduit terminates at both ends of the borehole and are joined in a header system 100, as shown in cut-away view FIG. 19C. The borehole 12 with multiple conduits 28 that are reduced at a header 100 continues as a single line 34 into the structure 40 and to the ground source heat pump 38.

In another alternative exemplary embodiment, the conduits of the subterranean continuous loop heat exchanger are arranged in series in a plurality of boreholes or are arranged in parallel in a plurality of boreholes. The choice to utilize a series or parallel arrangement for the conduits can be based on, among other things, the geological and thermal characteristics of the strata, the site dimensions and structure locations, and the load requirements.

The structures and apparatus associated with the subterranean continuous loop heat exchanger can be constructed by using any suitable means. For example, in one exemplary embodiment including at least one continuous borehole, a first portion of the borehole is formed by boring into a strata from a first opening. A second portion of the borehole is formed by boring into the strata from a second opening to join the second portion to the first portion to form the continuous borehole. A conduit for a fluid is then positioned in at least a portion of the borehole and is operationally connected to a supply line and to a return line for connection to a ground sourced heat pump. As previously described and shown herein, for example in FIGS. 1 to 4, the first opening and the second opening are separated by a predetermined distance and a first thermal envelope of the borehole at the first opening and a second thermal envelope of the borehole at the second opening are substantially independent. Further, a major length of the borehole is non-horizontal.

FIG. 20 schematically illustrates the construction of a subterranean continuous loop heat exchanger including at least one continuous borehole at an intermediate stage of construction. In the illustrated view 200, the first portion 202 of the borehole and the second portion 204 of the borehole are shown prior to being joined. Suitable equipment to form the borehole includes a drilling rig, suitable drilling fluids, drilling motor, drilling bit, fluid or air hammer, all which may use additional mechanical means underground to aid in the movement from the distal end to the proximal end, directional guidance apparatus, drilling fluid mixing, injection and recovery systems, drilling fluid and solids control system, directional drilling logging and reporting system(s). Suitable equipment to complete the borehole ready for thermal fluid transport could include mechanisms for the attachment of conduit(s) to be inserted, pushed and/or pulled through the borehole as the drilling media is removed, thermal grout mixing, injecting and placement equipment to ensure thermal grout is placed throughout the entire borehole, thermal fluid, equipment to pressure test the conduit integrity, and thermal testing equipment to verify thermal resistance of the borehole.

In order to form the borehole, care should be taken to ensure the proper directional orientation of the drilling bit at all times. In one exemplary embodiment, one can use mechanical, electronic, pulse, sonic, electromagnetic, magnetic and non-magnetic directional guidance tools manufactured or services provided by a variety of companies. Other effective guidance tools include beacons and signal emitters to guide the drilling through the borehole that may operate on any one of the aforementioned operational platforms. For example, a guiding device can be used to assist in boring the second portion 204 to join the first portion 202. An example of a guiding device includes one or more of a beacon 220 located in the first portion 202 and a sensor 222 in the second portion 204. The sensor 222 is in operational contact with a sensor monitor 224 that can be located in the operators station of the drilling rig. An output from the sensor monitor 224 can be used to guide the boring of the second portion 204 to join the first portion 202. For example, the output can be sent to a monitoring system 226 to allow a user to guide the drilling in real time. In this example, the guiding device can use a radio frequency, electrical signal, a magnetic field or an acoustic signal. In FIG. 20, the directional guidance tools are incorporated into a coiled tubing drilling and or steering assembly unit 230 with one or more drill string orientation device(s) that aid in directing the boring device in the desired direction.

FIG. 21 illustrates another example of forming a borehole showing the first portion 202 of the borehole and the second portion 204 of the borehole prior to being joined. In this illustrated example, a length of pipe or tubing called a casing 212 by those skilled in the art, is used to line the inside of the borehole and is placed in the first completed borehole section 202 through opening 208. In this exemplary embodiment, the casing will extend down into the ground a distance just exceeding the depth of unconsolidated overburden or material 18A, and just into the next level of strata 18B. The illustration also provides example of a second section of casing 216 placed into the second borehole 204 at the start 210 that extends through the unconsolidated strata level 18A and into the next strata 18B. The casing can be made of a variety of ferrous or nonferrous metals or alloys, or alternatively synthetic materials, the surfaces of which may be completely or partially coated, painted or otherwise have treated.

In this cross-section of an exemplary embodiment of a borehole the casing prevents the borehole from prematurely closing before the conduit 206 can be placed and secured. The casing can have an alternative purpose of aiding in the recovery of drilling fluids and the movement of cuttings generated from the drilling of the borehole to surface.

In most circumstances the casing will be removed from the borehole after the conduit is tested for integrity and the vacant spaces within the borehole are filed with grout.

Alternatively, the borehole could be drilled in one continuous loop without stopping, as shown in FIGS. 22-24.

FIG. 22 illustrates an exemplary embodiment of a subterranean continuous loop heat exchanger with a borehole drilled in a continuous loop through the earth. In this example, the conduit 206 is attached to a connector or coupler 229 which itself is operationally attached to a barrel reamer 232 or similar device, which is connected to the drill string 236.

In this example, the barrel reamer has a conical shaped leading edge and transitions into the body of the reamer that will be of a diameter roughly equal to the diameter or gauge of the borehole. The reamer has the purpose of compacting any residual cuttings or excess material to the walls of the borehole to assist in the smooth placement of the conduit.

Further illustrated is a device 230 that will guide or push the conduit using passive or active mechanical means to position or aid in the placement of the conduit into the borehole. The conduit guide or injection unit, 230 may or may not be in operational control with the main body of the conduit 228. For example, the main body of the conduit may be several feet, alternatively several hundred feet, away from the guide or injection unit. In another exemplary embodiment, the guide or injection unit may be anchored to the ground to provide stability and operationally increase the force applied to the conduit. The force applied can be varied and controlled by an operator directly in control of the unit, or alternatively by an operator simultaneously controlling the removal of the drill string 236 on the drilling rig 242. In this example, the drilling rig is represented by a model of a coiled tubing unit 242. The conduit guide or injection device 230 may be connected via a cable 231 with the drilling rig. The connection is to provide operational control over the guide and injection unit as to ensure the rate at which the conduit is guided or pushed into the borehole is the same rate as the drill string is removed at the other end. Further examples of a connection of the drilling rig to the injection unit are radio transmitters that with operational control either on the drill rig, or alternatively on the guide unit, or alternatively an operator independent of the either unit.

The guide or injection unit will have the capability to manage one or more conduit(s) simultaneously. Alternatively, the guide unit may apply operational control over one conduit and not others in the same borehole. In all examples, the guide or injector will help to reduce or eliminate the drag or friction on the conduit as it is being drawn back through the borehole and to ensure the conduit does not sustain damage that may affect the integrity of the conduit under pressure.

FIG. 23A schematically illustrates another example of the construction of a subterranean continuous loop heat exchanger including one continuous borehole. In this example, the drilling rig 244 is represented by a model of a truck mounted rotary unit is forming the subterranean continuous loop by drilling continuously from as first end 252 to a second end 254. In the example in FIG. 23A, the borehole 260 has a substantially vertical portion 262 at both the first end 252 and the second end 254.

In this example, a conduit 206 has been placed in the entire length of the borehole 260 extending from the borehole at the start 252 and at the other end 254. The borehole was subjected to pressure testing to verify the integrity of the conduit under pressure. Upon completion of pressure testing, the borehole grout 270 is mixed in this illustrated example of a mixing unit 248. The grout mixing unit is operationally connected via a hose or conduit 250 to the drilling rig 244 and the mud pump for the drilling rig 256. In this illustration, the mud pump 256 is located upon and is in operational contact with the drilling rig 244. In another example, the mud pump may be an operational component of the grout mixing unit 248. The grout is then pumped into the borehole 260 at the start 252 and pumping will continue until the grout protrudes from the end of the borehole 254, effectively filling all void spaces within the borehole. FIG. 23B shows the end of the borehole 254 with the conduit 206 protruding and the borehole full to the surface with grout 270. In this example, the casing has been removed from the distal end 254 prior to grout being placed in the borehole.

FIG. 23A also provides an illustration after the casing has been removed and a trench dug down into the ground to a depth not directly affected by seasonal temperature fluctuations. The borehole terminates within the trench and a header will be attached to the conduit 206 for directing the thermal fluid as desired. Upon successful completion of the grout placement, the casing at the start 252 will be removed from the ground and a similar trench will be formed to complete the borehole.

In FIGS. 21, 22, 23A-B, the use of casing is illustrated in several configurations. This is not to limit or exclude other examples of the use of casing in the formation of a borehole but only to provide illustrative examples. The decisions for the use of casing will be defined by the variables found in the ground identified as desirous to have a borehole placed. Therefore, the type, configuration, and use of casing is subjective and as varied as the ground conditions presented, as understood by those skilled in the art.

FIG. 24 illustrates an exemplary embodiment of a subterranean continuous loop heat exchanger with a borehole drilled in a continuous loop through the earth and a method of placing thermal grout into the borehole. In the example in FIG. 24, the borehole 260 has a substantially continuous curvature relative to the surface of the ground and shows the conduit 206 was placed in the borehole from the end 254 to the start 252. Further illustrated in FIG. 24, a tremie line 280 was inserted into the borehole with the conduit 206 in the same manner and pulled to the start of the borehole 252. It is further illustrated that the drilling rig and the conduit guide and placement systems are removed from the immediate proximity of the borehole leaving the tremie line retrieval and storage system 280, the grout mixing unit 248 and grout pumping system 256 attached, which is in operational contact with the tremie line carrier 280 via a grout transfer conduit 250. In this example the grout pump 256 will accept grout 270 from the mixer 248 and pump it via transfer conduit 250, the length of the tremie line 280 to the starting end of the borehole 252. As the borehole fills with grout the tremie line will be slowly be pulled back through the borehole filling all the vacant spaces with grout until the tremie line emerges from the borehole at the end 254.

FIG. 25 illustrates a volume of earth 300 in which has been positioned a subterranean continuous loop heat exchanger. As can be seen, the subterranean continuous loop heat exchanger traverses several strata 18A-18E and is advantageously positioned for its desired heat exchange function. It has been identified by those skilled in the art that one stratum will exhibit higher thermal conductivity than other adjacent. Further to this, once the desired stratum has been identified it would be advantageous to place a substantial portion of the borehole within this stratum as illustrated in this case by the example of strata zone 18C. Further illustrated in FIG. 25 the separation distances of the borehole (D_(S)) and the thermal envelopes (D_(E)) are substantially independent at the surface of the ground and at depth.

FIG. 26 illustrates a coil tubing rig 242 positioned over a casing 212 and has completed drilling a borehole 12 in one continuous loop. In the example, the coiled tubing 236 was directed back to surface operationally behind the drilling rig 242 with the help of the drilling motor 230 and directional guidance 222. Additionally aiding in the formation of the predominantly curved borehole was the curvature or natural memory curvature resident in the coiled tubing 236 from being spooled onto the coiled tubing carrier and storage spool 248.

Coiled tubing is subjected to compressive forces upon being removed from the coiled tubing carrier 248 and passing through the neck 258 and the coiled tubing injection head 264 with the expressed purpose of straightening the coil tubing before it is inserted into the ground. It has been found that by manipulating or adjusting the force applied on the coiled tubing by the neck and the injection head, the amount of residual memory left in the coiled tubing and or the direction of the bend after the tubing had left the injection head could be increased or decreased, as it was found that, in some instances, it was advantageous to increase the amount of bend on the coil to, in affect, amplify the curvature. The beneficial aspects of manipulating the residual memory and or increasing the curvature of the coil tubing helped in the drilling of the curved portion of the subterranean borehole.

FIG. 26 illustrates the coil tubing traveling in a direction through the earth in a loop back to surface behind the drilling rig 242. In other exemplary examples, the coil tubing can have the curvature manipulated to aid in the drilling of a borehole as illustrated, for example, in FIG. 21 or FIG. 22, as understood by those skilled in the art.

Although described herein as boring, other suitable means of forming the borehole includes drilling, vibrating, augering, hammering, or jetting. In most instances there is a need to set temporary or permanent casing in the uppermost section of the borehole starting at surface. Additionally, the use of conventional rotary drilling systems, hydraulic rotary drilling systems, vibratory drilling systems, slant hole drilling systems, coil or coiled tubing systems, specialized drilling motors or turbine drilling motors, ramming, jetted boring tools can be used to form a borehole. Optional equipment and systems can include guides, electric and or mechanical means to advance the drilling tool(s) and or casing and drill pipe or tubing, as is know by those skilled in the art.

Additional construction includes positioning a heat exchange medium within an annulus between an inner wall of the borehole and an outer surface of the conduit. As previously described herein, the heat exchange medium contributes to a thermal exchange with a surrounding strata.

The disclosed subterranean continuous loop heat exchanger can be utilized to (i) provide heating to a structure, (ii) provide cooling to a structure, or (iii) store energy for future use. Further, the disclosed subterranean continuous loop heat exchanger can be utilized to provide more than one function by, for example, provide heating to a first structure and providing cooling to a second structure. In one such example, the disclosed subterranean continuous loop heat exchanger can be utilized to provide heating to a first structure containing a swimming facility and to provide cooling to a second structure containing a skating facility.

Generally, in the example of using a ground source heat pump in heating mode the cold fluid is pumped in from one end of the subterranean continuous loop heat exchanger and warms as it travels through to the other of the subterranean continuous loop heat exchanger. Over the course of the heating season this will somewhat cool the strata surrounding the borehole. In the cooling season, the fluid is reversed through the borehole and fluid flowing though the subterranean continuous loop heat exchanger begins to somewhat warm the surrounding strata. In utilizing industry standard formulas for calculating thermal resistance and thermal conductivity, large gains in borehole efficiency have been identified in every configuration utilizing a subterranean continuous loop heat exchanger as disclosed herein. Depending upon the requirements of the building envelope, a certain amount of energy in either the form of cold thermal fluid being circulated into the subterranean continuous loop heat exchanger during periods of building heating loads, or hot thermal fluid circulated during periods of building cooling load requirements are used.

In view of the above, an exemplary method of regulating a temperature in a structure comprises flowing a fluid through a conduit in a borehole of a subterranean continuous loop heat exchanger from an entrance to an exit. From the exit, the fluid flows through a ground sourced heat pump or heat exchanger system and is returned from the ground sourced heat pump or heat exchanger system to the entrance of the subterranean continuous loop heat exchanger. The ground sourced heat pump is operated to regulate the temperature in the structure. The conduit for a fluid positioned in at least a portion of the subterranean borehole is in operational connection to a supply line and to a return line for connection to the ground sourced heat pump. Further, the entrance and the exit are separated by a predetermined distance and a first thermal envelope of the borehole at the entrance and a second thermal envelope of the borehole at the exit are substantially independent.

When the heating and air-conditioning “load” is calculated for a structure (measured in nominal tons of energy) a corresponding amount of energy required to expel into the subterranean heat exchanger(s) and/or, an amount of energy needed to be taken from the subterranean heat exchangers, is defined. The engineer or designer specifies the subterranean heat exchanger design that will meet the thermal energy conversion requirements in the most cost efficient configuration. Further calculations then define the size of subterranean heat exchanger field required. In the case of vertical boreholes the calculation generally will produce a number of linear feet of borehole required based upon the thermal efficiency of the strata in the area.

Although described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without department from the spirit and scope of the invention as defined in the appended claims. 

1. A subterranean continuous loop heat exchanger, comprising: a borehole including an entrance at a first end and an exit at a second end; a conduit for a fluid, the conduit positioned in at least a portion of the borehole and in operational connection to a supply line and to a return line for connection to a ground sourced heat pump or a heat exchanger system; wherein the entrance and the exit are separated by a predetermined distance and a first thermal envelope of the borehole at the entrance and a second thermal envelope of the borehole at the exit are substantially independent, wherein a direction of fluid flow relative to the borehole is unidirectional, and wherein a major length of the borehole is non-horizontal.
 2. The subterranean continuous loop heat exchanger of claim 1, comprising a heat exchange medium positioned within an annulus (preferably the entire annulus) between an inner wall of the borehole and an outer surface of the conduit, the heat exchange medium contributing to a thermal exchange with a surrounding strata.
 3. The subterranean continuous loop heat exchanger of claim 1, wherein the conduit can include a flow enhancement feature placed in a fluid flow stream within the conduit.
 4. The subterranean continuous loop heat exchanger of claim 3, wherein the turbulence feature includes a plurality of ribs on an inner surface of the conduit.
 5. The subterranean continuous loop heat exchanger of claim 4, wherein the flow enhancement feature includes a raised profile on one or more of an inner surface of the conduit.
 6. The subterranean continuous loop heat exchanger of claim 3, wherein the flow enhancement feature includes an insert positioned within the conduit.
 7. The subterranean continuous loop heat exchanger of claim 6, wherein the insert has a spiral shape or a helical shape.
 8. The subterranean continuous loop heat exchanger of claim 6, wherein the insert is a twisted ribbon of metal, metal alloy or a synthetic material.
 9. The subterranean continuous loop heat exchanger of claim 1, wherein the conduit includes a raised profile on one or more of an outer surface of the conduit and an inner surface of the conduit.
 10. The subterranean continuous loop heat exchanger of claim 1, comprising a plurality of conduits for a fluid, each conduit positioned in at least a portion of the subterranean borehole and in operational connection to the supply line and to the return line for connection to the ground sourced heat pump or to the heat exchanger system.
 11. The subterranean continuous loop heat exchanger of claim 1, wherein the conduit is a tube or pipe formed from a metal, a metal alloy or a synthetic material.
 12. The subterranean continuous loop heat exchanger of claim 1, wherein operational connection of the conduit to the supply line and to the return line includes a header system.
 13. The subterranean continuous loop heat exchanger of claim 1, wherein the predetermined distance is at least about fifteen feet.
 14. The subterranean continuous loop heat exchanger of claim 1, wherein the predetermined distance is between about one foot and about five feet.
 15. The subterranean continuous loop heat exchanger of claim 1, wherein the predetermined distance is based on a thermal capability of the strata containing the heat exchanger and a load requirement of a structure, a temperature of which is to be regulated by the ground source heat pump or by the heat exchanger system.
 16. The subterranean continuous loop heat exchanger of claim 1, comprising a plurality of boreholes, wherein the conduit is positioned in series in the plurality of boreholes.
 17. The subterranean continuous loop heat exchanger of claim 1, comprising a plurality of boreholes, wherein the conduit is positioned in parallel in the plurality of boreholes.
 18. The subterranean continuous loop heat exchanger of claim 1, wherein at the entrance of the borehole and at the exit of the borehole, a centerline of the borehole is within ±15 degrees of vertical.
 19. The subterranean continuous loop heat exchanger of claim 18, wherein at the entrance of the borehole and at the exit of the borehole, the centerline of the borehole is within ±5 degrees of vertical.
 20. A method of constructing a subterranean continuous loop heat exchanger, the subterranean continuous loop heat exchanger including at least one continuous borehole, the method comprising: forming a borehole by boring into a strata; positioning a conduit for a fluid in at least a portion of the borehole; and operationally connecting the borehole to a supply line and to a return line for connection to a ground sourced heat pump or a heat exchanger system; wherein a first opening of the borehole and a second opening of the borehole are separated by a predetermined distance and a first thermal envelope of the borehole at the first opening and a second thermal envelope of the borehole at the second opening are substantially independent, wherein a direction of fluid flow relative to the borehole is unidirectional, and wherein a major length of the borehole is non-horizontal.
 21. The method of claim 20, wherein forming the borehole by boring into the strata includes boring a first portion of the borehole from the first opening and boring a second portion of the borehole from the second opening to join the second portion to the first portion to form the continuous borehole.
 22. The method of claim 21, wherein a guiding device assists in boring the second portion to join the first portion, wherein the guiding device includes one or more of a beacon located in the first portion and a sensor in the second portion, the sensor in operational contact with a sensor monitor, and wherein an output from the sensor monitor is used to guide the boring of the second portion to join the first portion.
 23. The method of claim 22, wherein the guiding device uses a radio frequency, electric or mechanical signal, a magnetic field or an acoustic signal.
 24. The method of claim 20, wherein positioning the conduit includes positioning a conduit in the first portion of the borehole through the first opening and pulling the conduit toward the second opening into the second portion of the borehole.
 25. The method of claim 20, wherein positioning a conduit at the point at which the drilling media exits the earth and includes operationally attaching a conduit to the drilling media and pulling the conduit towards the first opening of the borehole.
 26. The method of claim 20, comprising positioning a heat exchange medium within an annulus between an inner wall of the borehole and an outer surface of the conduit, the heat exchange medium contributing to a thermal exchange with a surrounding strata.
 27. The method of claim 20, wherein the conduit includes a flow enhancement feature placed in a fluid flow stream within the conduit.
 28. The method of claim 27, wherein the flow enhancement feature includes a raised profile on one or more of an inner surface of the conduit.
 29. The method of claim 20, wherein the conduit includes a raised profile on one or more of an outer surface of the conduit and a raised profile on an inner surface of the conduit.
 30. The method of claim 20, wherein at the entrance of the borehole and at the exit of the borehole, a centerline of the borehole is within ±15 degrees of vertical.
 31. A method of regulating a temperature in a structure, the method comprising: flowing a fluid through a conduit in a borehole of a subterranean continuous loop heat exchanger from an entrance to an exit; flowing the fluid from the exit through a ground sourced heat pump or a heat exchanger system; returning the fluid from the ground sourced heat pump or from the heat exchanger system to the entrance; and operating the ground sourced heat pump or heat exchanger system to regulate the temperature in the structure.
 32. The method of claim 31, wherein the conduit is positioned in at least a portion of the borehole and in operational connection to a supply line and to a return line for connection to the ground sourced heat pump or to the heat exchanger system and wherein the entrance and the exit are separated by a predetermined distance and a first thermal envelope of the borehole at the entrance and a second thermal envelope of the borehole at the exit are substantially independent.
 33. The method of claim 31, wherein a direction of flow of the fluid relative to the borehole is unidirectional, and wherein a major length of the borehole is non-horizontal
 34. A method to store thermal energy in a subterranean continuous loop heat exchanger, the method comprising: flowing a fluid through a conduit in a borehole of a subterranean continuous loop heat exchanger from an entrance to an exit; flowing the fluid from the exit through a ground sourced heat pump or a heat exchanger system; returning the fluid from the ground sourced heat pump or from the heat exchanger system to the entrance; and operating the ground sourced heat pump or the heat exchanger system to exchange thermal energy with a strata surrounding the subterranean continuous loop heat exchanger.
 35. The method of claim 34, wherein the conduit is positioned in at least a portion of the borehole and in operational connection to a supply line and to a return line for connection to the ground sourced heat pump or to the heat exchanger system and wherein the entrance and the exit are separated by a predetermined distance and a first thermal envelope of the borehole at the entrance and a second thermal envelope of the borehole at the exit are substantially independent.
 36. The method of claim 34, wherein a direction of flow of the fluid relative to the borehole is unidirectional, and wherein a major length of the borehole is non-horizontal. 